1. The Field of the Invention
The present invention broadly relates to trailers for automotive draft vehicles. In one of its more specific embodiments, the invention is concerned with trailers of the type frequently used for transporting poles and other lengthy objects which are adjustable in length from a long-coupled or loaded position to a short-coupled or running position, or vice versa. The invention is also concerned with an improved coupling means whereby the effective length of the trailer may be easily adjusted between predetermined long-coupled and short-coupled positions.
2. The Prior Art
A wide variety of trailers for automotive draft vehicles have been proposed heretofore. One class of prior art trailers includes an elongated coupling member having a rear axle assembly slidably mounted thereon so as to be movable between longitudinally spaced long-coupled and short-coupled positions to thereby adjust the effective length of the trailer. As is well known in this art, it is often desirable to increase the effective length of a trailer when it is to be loaded with elongated objects such as poles, and then decrease the effective length after the poles have been unloaded and it is desired to make a return trip at high speed for an additional load. It is necessary to adjust the unloaded trailer to the short-coupled position for the return trip at high speed as there is a pronounced tendency otherwise for the rear axle assembly to weave back and forth across the road and thereby increase driving hazards. The general driving and operating conditions are also adversely affected when unloaded and operating at high speed in the long-coupled position.
Various types of coupling assemblies have been proposed for the purpose of adjusting the effective length of a trailer between the short-coupled and long-coupled positions. However, the coupling assemblies available heretofore have not been entirely satisfactory. For example, some of the prior art coupling assemblies were difficult for one person to operate and a helper was needed. In other instances, the prior art coupling assemblies did not allow the trailer to be both towed and backed by the draft vehicle in the short-coupled and/or the long-coupled positions, thereby greatly limiting the usefulness of the trailer under road and operating conditions where both forward and rearward movement of the trailer are highly desirable. In still other instances, the prior art coupling assemblies did not provide for transverse relative angular movement around the longitudinal axes of the coupling member and the rear axle assembly. This resulted in severe stress and strain and ultimate mechanical failure due to the relative angular movement imparted to the coupling member by the wheels of the draft vehicle, and to the rear axle assembly by the rear trailer wheels, when passing over rough terrain.
In view of the foregoing, an entirely satisfactory trailer for an automotive draft vehicle of the class described was not available prior to the present invention in spite of the long existing and great need therefor.